Refining mineral oil with oxygen and magnetically separated bauxite containing iron



United States atent ()fice Patented Sept. 2, 1958 REFINING MINERAL OIL WITH GXYGEN AND MAGNETICALLY SEPARATED BAUXKTE CUN- TAINING IRON Ivor W. Mills, Glenolden, and Peter B. Murray, Media, Pa., assignors to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing. Application January 6, 1955 Serial No. 480,296

2 Claims. c1. 196--29) The invention relates to the refining of mineral oil and more particularly to the conversion or removal of mercaptans and otherobjectionable sulfur compounds from mineral oil.

Various means have been proposed for converting or removing mercaptans from various mineral oil fractions such as gasoline, naphtha, etc., and some of the means which have been proposed may produce a product having satisfactorily low mercaptan content, but the life of the treating agent which is used may be unsatisfactorily short.

It has been proposed to use bauxite as a contacting agent to reduce mercaptan content of mineral oil. The bauxite which has been proposed is ordinary bauxite, which is obtained from the native mineral merely by thermal activation, generally at a temperature of 600- 700 F. or higher. It is possible, employing such bauxite, to reduce-the mercaptan content of mineral oil fractions to a quite low level, but after a certain amount of mineral oil has been contacted with a given portion of bauxite, the activity of the latter for reducing mercaptan content becomes decreased, whereupon the mineral oil products subsequently obtained from that bauxite will contain unsatisfactorily large amounts of mercaptans.

According to the invention, a process for reduction of mercaptan content by means of an adsorbent is provided wherein the life of the adsorbent is substantially increased. This makes it possible to treat mineral oil for substantially longer periods before having to regenerate or discard the adsorbent.

The process of the invention involves the contacting of mineral oil in liquid phase with a magnetically separated bamite containing 20 to 70 weight percent of iron compounds as Fe O Magnetically separated bauxite differs from ordinary bauxite in having been subjected to a process, as well known in the art, for magnetically separating bauxite particles having high iron content from bauxite particles having lower iron content. An ordinary bauxite, i. e. a native bauxite, which has not been treated for separation of particles having high iron content frorn particles having low iron content, may contain for example Weight percent of iron compounds as Fe O By magnetic separation, such bauxite can be separated into a high-iron fraction having iron con tent within the range from to 70 weight percent as Fe O and a low-iron fraction having iron content which is of course substantially lower than 15 weight percent as Fe O it has been found that a high iron, magnetically separated bauxite has considerably longer life for the reduction of mercaptan content of mineral oil than ordinarybauxite as employed in the prior art.

According to the invention, straight run or thermally or catalytically cracked mineral oil, e. g. gasoline, spirits,

naphtha, kerosene, etc., containing mercaptans, is contacted in liquid phase, e. g. by percolation of the mineral oil through a bed of the bauxite or otherwise, with bauxite which has been obtained by magnetic separation and contains 20 to Weight percent, preferably 40 to 60 weight percent, of iron compounds as Fe O Preferably, the bauxite has also been thermally activated, either before or after the magnetic separation, in a man- .er known in the art. Preferably, the contacting is performed at atmospheric temperature and pressure. Elevated temperatures can be employed if desired, for example up to 250 F. However, such elevated temperatures are not necessary for eflicient reduction of mercaptan content, and may have an adverse effect upon the gum rating of the product obtained in the operation, particularly in the case of a cracked charge stock.

it is believed that the process of the invention involves not merely physical adsorption of constituents of the charge on the magnetically separated bauxite, but an oxidation of mercaptan constituents, and that the presence of oxygenis therefore required during the contact of adsorbent with hydrocarbon material. Frequently, the latter will contain sufficient oxygen, in the form of air, without employing any additional oxygen. If additional oxygen is needed, it may be added to the hydrocarbon material prior to the bauxite treatment, or introduced directly into the treating zone.

.The following example illustrates the invention:

Thermal gasoline containing 0.0010 to 0.0012 weight percent of mercaptan sulfur was percolated at atmospheric temperature and pressure through a bed of magnetically separated, thermally activated bauxite containing about 55 weight percent of iron compounds as F6203- The bauxite had been pre-dried at 400620 F. and about 1 mm. Hg. for 23 hours. The space rate was 8 for the first 4000 cc. percolated through the bed and 5.5 for the next 12,000 cc. Separate samples of efiluent gasoline were collected, the size of each sample being 4000 cc. The bulk volume of the bed was 60 cc. Each effluent sample was tested for mercaptan content by titrating with a standard aqueous solution containing copper ions. The amount of efiluent collected before the ercent mercaptan sulfur of the efiluent substantially exceeded 0.0001 percent was determined. This amount indicated the capacity of the bauxite for producing gasoline having mercaptan content not exceeding 0.0001 percent.

For purpose of comparison, another run was made under similar conditions but employing ordinary thermally activated bauxite containing about 15 weight percent of iron compounds as Fe O in place of the magnetically separated bauxite. The bauxite had been predried at 400-620" F. and about 1 mm. Hg. for 3 hours. The following table shows the results obtained:

Bauxite: Capacity, cc. Ordinary 8000 Magnetically separated 16,000

This example shows that magnetically separated bauxite is capable of reducing twice as much thermal gasoline to a mercaptan content not exceeding 0.0001 percent, as ordinary bauxite.

In copending application Serial No. 478,768, filed December 30, 1954, by the present inventors, methods for reducing the mercaptan content of hydrocarbons are disclosed and claimed, such methods including inter alia contacting hydrocarbons containing mercaptans in liquid phase with a treating agentprepared by contacting granular, magnetically separated bauxite with an alkali.

The invention claimed is:

1. Method for reducing the mercaptan content of mineral oil which comprises contacting mineral oil containing mercaptans in liquid phase in the presence of oxygen with magnetically separated bauxite containing about 20 to 70- weight percent of'iron compounds as Fe O 2. Method according to claim 1 wherein said contacting is performed at a temperature not substantially above- References Cited in the file of this patent UNITED STATES PATENTS 

1. METHOD FOR REDUCING THE MERCAPTAN CONTENT OF MINERAL OIL WHICH COMPRISES CONTACTING MINERAL OIL CONTAINING MERCAPTANS IN LIQUID PHASE IN THE PRESENCE OF OXYGEN WITH MAGNETICALLY SEPARATED BAUXITE CONTAINING ABOUT 20 TO 70 WEIGHT PERCENT OF IRON COMPOUNDS AS FE2O3. 